With the advent of mobile stations and wireless communication systems, mobile subscribers are granted location independent mobility with a number of other features and applications. One such feature is a detachable subscriber identification module identifying a particular mobile subscriber or associated subscription account. With a mobile station having a detachable subscriber identification module, such as a Subscriber Identity Module (SIM) in a Global System for Mobile (GSM) communication system, a mobile subscriber conveniently exchanges or changes his mobile equipment by merely removing his SIM card from the old mobile equipment and re-inserting it into the new mobile equipment. As a result, the mobile user no longer has to rely on a customer support or technicians to switch his mobile equipment from the old equipment to the new equipment while still retaining the same telephone number along with his personal settings and user information. However, with the physical separation between a subscriber identity module (SIM) identifying a particular mobile subscriber and particular mobile equipment providing wireless communications, two different identification data are needed for properly validating the mobile subscriber (or subscription) as well as the associated mobile equipment within the wireless communications network. As an illustration, a mobile equipment within a GSM network for communicating voice and a General Packet Radio System (GPRS) network for communication data is identified using an International Mobile Equipment Identification (IMEI) as standardized by the 3rd Generation Partnership Project (3GPP) Standard. Separately, as discussed above, mobile subscriber identification data or subscription data are identified using an International Mobile Subscriber Identity (IMSI) as further standardized by the GSM Standard, or, alternatively, using an Universal Mobile Subscriber Telephony System (UMTS) SIM (USIM), as standardized by the 3GPP Standard.
To determine whether mobile equipment is permitted within a particular mobile communication network, a permission status check on the mobile equipment needs to be performed. A permission status check performed on an IMEI as identification data for particular mobile equipment may be referred to as IMEI check. Such a permission status check is performed for a various reasons. One such reason may be to detect stolen mobile equipment. It may also be to detect virus infected mobile equipment which should not be granted access to a mobile network. The permission status check could also be used for performing “type approval” in order to identify mobile equipment not approved for use within a particular mobile network for technical, regulatory or compatibility reasons. A regulatory reason may be to “type approve” a particular terminal type as to not disturb other technical installations. Another technical reason may be to approve a particular terminal as to properly cooperate with existing network equipment within a mobile network.
The IMEI check for conducting the above described permission status check may be performed using a mobility management component in a Visitor Location Register (VLR) within the GSM network architecture or in a Serving GPRS Support Node (SGSN) within the GPRS network architecture. More specifically, an IMEI check is performed during a call control procedure for a call setup in a VLR serving a particular mobile station within a GSM network or, during a session management procedure, for a location area update, or for an attach procedure in an SGSN serving that mobile station within a GPRS network. An IMEI check may be further performed according to one or more rules defined by a serving SGSN or VLR further specifying when or how often an IMEI check needs to be performed for a served mobile station.
Reference is now made to FIG. 1 which is a block diagram illustrating a network architecture for GSM/GPRS networks which may be used in accordance with the above described permission status check procedures. Such a mobile network (MN) 5 comprises a mobile station (MS) 1, which comprises mobile equipment (ME) 11 and subscriber identity module (SIM) or UMTS SIM (USIM) 12. The MS 1 is connectable to a serving core network (CN) 3 via a radio network (RN) 2. One skilled in the art would understand that such a radio network would include base station transceivers (BTSs, not shown in FIG. 1) and base station controllers (BSCs, not shown in FIG. 1) for providing wireless communication links to the MS 1. The core network (CN) 3 further includes a Mobile Services Switching Center & Visitor Location Register (MSC/VLR, collectively herein after also referred to as the MSC) for switching voice calls and Serving GPRS Support Node (SGSN) for switching packets or data for the serving MS 1. Even though an MSC provides voice connection for a GSM system and an SGSN provides packet or data connection within a GPRS system, the MSC and SGSN 31 are illustrated as being co-located and residing on a single platform in FIG. 1. However, one skilled in the art would understand that MSC (including VLR) and SGSN could easily be located as two separate network nodes and independently functioning and interacting with the RN 2. The CN 3 is, in turn, connected to other Public Land Mobile Network (PLMN) or other Public Switched Telephone Network (PSTN) 4 for communicating with other networks, terminals and destinations.
To provide permission status check and subscriber validation process, the core network 3 further includes two different databases—an Equipment Identity Register (EIR) 32 as an equipment related database and a Home Location Register or Home Subscriber Server (HLR/HSS) 33 as a subscriber related database. The EIR 32 stores the IMEI data along with the associated permission status for the ME 11. The permission status may be requested by the MSC/SGSN 31 as described above using permission status request signals sent via an interface between MSC/SGSN 31 and EIR 32. The interface between MSC and EIR in the GSM network architecture is refereed to as an F interface and the interface between SGSN and EIR in the GPRS network architecture is referred to as a Gf interface.
The HLR/HSS 33 on the other hand is a centralized subscriber database handling subscriber related data. Subscriber related data may be requested by the MSC/SGSN 31 via an interface towards HLR/HSS 33 using the associated IMSI data identifying a particular mobile subscriber or subscription. For example the HLR/HSS 33 stores the IMSI associated to SIM/USIM 12 as subscriber related identification data.
Reference is now made to FIG. 2 illustrating a signal sequence diagram for performing both the mobile equipment permission status check as well as the subscriber validity check as performed in the conventional GSM/GPRS system as depicted in FIG. 1. More specifically, FIG. 2 describes a permission status check performed during a “network attach” procedure “attaching” a mobile station 1 to a particular mobile network 5. To request a registration with an MSC/SGSN 31, the MS 1 sends an attach request signal 201 to the MSC/SGSN 31. The attach request 201 includes the International Mobile subscriber Identity (IMSI) number associated with the SIM/USIM 12 (shown in FIG. 1) of the MS 1. After receiving the attach request signal 201 from the MS 1, the serving MSC/SGSN 31 then determines whether there is a need to perform a permission status check on the requesting mobile equipment in a process IMSI step 231. Such a determination can be made by determining whether a permission status check on that particular mobile equipment associated with the identified IMSI number has been previously performed by the serving MSC/SGSN 31. Alternatively, the MSC/SGSN 31 may determine to perform a permission status check based on a statistical determination or, preferably, in the event the mobile equipment has not been checked for a long period of time or for a number of preceding attach procedures. In any event, in response to a determination that the mobile equipment needs to be checked, the serving MSC/SGSN 31 then requests the IMEI number associated with the mobile equipment (ME) 11 serving that particular mobile subscriber. The MSC/SGSN 31 therefore sends an identity request signal 202 to the MS 1 requesting the MS 1 to provide the network with its equipment identification number. In response, the MS 1, for example, provides the IMEI number in an identity response signal 203 back to the MSC/SGSN 31.
In response to receiving the IMEI associated with ME 11, the MSC/SGSN performs a permission status check on the IMEI associated with ME 11 by sending a check IMEI signal 211 towards the EIR 32. The EIR 32 then looks up the current permission status associated with ME 11 and responds with a check IMEI response signal 212 containing the permission status of the ME 11. Such permission status may indicate the identified ME as being “white listed” indicating that the respective mobile equipment is deemed to be permitted for use, as being “black listed” indicating that the respective mobile equipment is deemed not permitted for use and should be barred, or as being “gray listed” indicating that the respective equipment is deemed permitted for use but should be monitored. According to the permission status of ME 11 indicated in the check IMEI response signal 212, MSC/SGSN then determines whether to accept or reject the requested attach procedure 201.
In case of a positive determination that the attach request is to be approved for that particular MS1, the serving MSC/SGSN 31 then performs yet another validation process by sending a update location request signal 221 to a HLR/HSS 33 associated with the identified IMSI number. The serving HLR/HSS 33, in turn, performs subscriber validation process to determine whether this particular mobile subscriber should be granted access to that particular mobile network and provides a update location response signal 222 with the access status back to the requesting MSC/SGSN 31.
As illustrated, it is rather inefficient for the serving MSC/SGSN to perform two different status checks or validations with two multiple databases. Accordingly, there is a need for simplified network architecture and more efficient signaling procedures to perform status checks on the mobile equipment as well as the mobile subscriber.